Japanese Patent Laying-Open No. 2000-295715 (hereinafter referred to as PTL 1) describes a power supply system for an electric vehicle in which electric power is supplied from two DC power sources to a load (vehicle driving electric motor). In PTL 1, two electric double layer capacitors are used as DC power sources. It is described that an operation mode is provided in which the two electric double layer capacitors are connected in parallel for supplying electric power to the load.
Japanese Patent Laying-Open No. 2008-54477 (hereinafter referred to as PTL 2) describes a voltage converting device having a plurality of DC voltages as inputs and outputting a plurality of DC voltages. In the voltage converting device described in PTL 2, operation modes are switched by switching connection between a terminal of energy storage means (coil) and a plurality of input potentials as well as a plurality of output potentials. The operation modes include a mode in which two DC power sources are connected in parallel for supplying electric power to the load.
Further, Japanese Patent Laying-Open No. 2010-57288 (hereinafter referred to as PTL 3) describes a configuration of an electric power supplying device including first and second power storage units, provided with a switch for switching series connection and parallel connection between the power storage units.